[Xen-devel] [Patch V6 11/16] xen: check for initrd conflicting with e820 map

[Juergen Gross <jgross@xxxxxxxx>]

Check whether the initrd is placed at a location which is conflicting
with the target E820 map. If this is the case relocate it to a new
area unused up to now and compliant to the E820 map.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@xxxxxxxxxx>
---
 arch/x86/xen/setup.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 3fca9c1..0d7f881 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -632,6 +632,36 @@ phys_addr_t __init xen_find_free_area(phys_addr_t size)
 }
 
 /*
+ * Like memcpy, but with physical addresses for dest and src.
+ */
+static void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src,
+                                  phys_addr_t n)
+{
+       phys_addr_t dest_off, src_off, dest_len, src_len, len;
+       void *from, *to;
+
+       while (n) {
+               dest_off = dest & ~PAGE_MASK;
+               src_off = src & ~PAGE_MASK;
+               dest_len = n;
+               if (dest_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off)
+                       dest_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off;
+               src_len = n;
+               if (src_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off)
+                       src_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off;
+               len = min(dest_len, src_len);
+               to = early_memremap(dest - dest_off, dest_len + dest_off);
+               from = early_memremap(src - src_off, src_len + src_off);
+               memcpy(to, from, len);
+               early_memunmap(to, dest_len + dest_off);
+               early_memunmap(from, src_len + src_off);
+               n -= len;
+               dest += len;
+               src += len;
+       }
+}
+
+/*
  * Reserve Xen mfn_list.
  * See comment above "struct start_info" in <xen/interface/xen.h>
  * We tried to make the the memblock_reserve more selective so
@@ -810,6 +840,27 @@ char * __init xen_memory_setup(void)
 
        xen_reserve_xen_mfnlist();
 
+       /* Check for a conflict of the initrd with the target E820 map. */
+       if (xen_is_e820_reserved(boot_params.hdr.ramdisk_image,
+                                boot_params.hdr.ramdisk_size)) {
+               phys_addr_t new_area, start, size;
+
+               new_area = xen_find_free_area(boot_params.hdr.ramdisk_size);
+               if (!new_area) {
+                       xen_raw_console_write("Can't find new memory area for 
initrd needed due to E820 map conflict\n");
+                       BUG();
+               }
+
+               start = boot_params.hdr.ramdisk_image;
+               size = boot_params.hdr.ramdisk_size;
+               xen_phys_memcpy(new_area, start, size);
+               pr_info("initrd moved from [mem %#010llx-%#010llx] to [mem 
%#010llx-%#010llx]\n",
+                       start, start + size, new_area, new_area + size);
+               memblock_free(start, size);
+               boot_params.hdr.ramdisk_image = new_area;
+               boot_params.ext_ramdisk_image = new_area >> 32;
+       }
+
        /*
         * Set identity map on non-RAM pages and prepare remapping the
         * underlying RAM.
-- 
2.1.4


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